Tim Buckwalter's notation is a one-to-one transliteration of the Arabic script for Modern Standard Arabic, using lower ASCII characters to encode the graphemes of the original script. This system has been very popular in Natural Language Processing, however, there are limits to its applicability due to numerous non-alphabetic codes involved.

If the first element in the list to use is :xml, the alternative mapping is introduced that suits the XML etiquette. This option is there only to replace the >&< reserved characters by OWI while still having a one-to-one notation. There is no XML parsing involved, and the markup would get distorted if subject to decode!